Muti007

So I know our trucks are full time 4wd. I was thinking most times we dont really need all out 4wd, though I am only going to be really driving mine in inclement weather with rain or snow or for roadtrips, otherwish shell more or less just sit and go out for the occasional car wash and wax. My DD is my other LExus and my summer car is the S2000.

So then I was thinking about the ability to disengage the center locking diff and it got me thinking. Why would I ned that engaged for everyday driving? If that is off, are you still 4wd or are you now rwd? Im really not sure so I figured I would ask. If youre not driving through crazy treacherous snow, deep rain puddles, shallow lakes mud or the like, should you drive with it disengaged? If so, exactly what are all 4 wheels doing at that point?

stiles_s

The torsen diff is pretty efficient, so you aren't losing much in terms of efficiency having it drive all 4 wheels. How in the world would you disengage the diff? Pull the half-shafts?

Torsen has been the center diff for Audi Quattros for the last 15'ish years (except for the transverse-engined Audis like the TT and A3). I've never heard of anyone converting one to 2wd.

Muti007

Maybe Im saying it wrong, in which case I apologize. I am referring to the button with the x between the front and rear wheels. Maybe it is more accurate to say the center transfer case? What is the benefit to running with this engaged all the time rather than running with it disengaged?

Sweep

When you are driving around with the center diff unlocked it is more akin to AWD with a heavy layer of traction control and stability control. When you lock the center diff with the button on the center console you are making 4wd like any other truck.

With the center diff locked it will be hard to maneuver in tight areas on dry pavement. Only use the center diff lock in really bad weather or if the traction control is hindering your forward movement such as: Mud, sand, DEEP snow. Typically you will be fine with the AWD as it affords you 80% of the grip of 4WD with none of the handling side effects.

cdew002

You do not want to drive around town with a locked diff. Turn it off.

Sweep

^^ This. ^^

cdew002

And technically speaking (just for your trivia knowledge bank), pressing the button actually disables the center differential. When engaged, the center differential allows you to run 4wd safely on pavement by letting the front and rear axle spin independently.

ALAN553

Read the manual, locking the diff is only when you are on slippery surfaces. The front wheels are locked and turn at the same speed. When turning the inside wheel needs to turn slower and if the diff is locked the tire will scrub the pavement. Not good. With the diff unlocked the truck operates as a rear wheel drive until the front senses a slip and then comes into play.

Muti007

Thank you everyone, this is what I was asking and now I have my answer and get it. I thought when I hit the button and it flashed on the dash, THEN i was unlocking it. It is in fact the opposite! By default you are driving it with it disengaged and with VSC on. When you hit the button, you are then engaging the center diff and turning VSC off. That is what I didnt get and do now.

Thanks!

cdew002

Close.

Think of it this way; for full time 4wd vehicles, the center diff was included to allow the forward and rear axles to turn independently of one another. Without the center diff, your axles would turn together, regardless of conditions, causing unnecessary wear.

Because there are times that you want the forward and rear axle turning in concert (i.e. one set of tires unable to get traction), Toyota kindly put a button on our vehicles that would allow us to have 50/50 front/rear power when needed.

Muti007

Ok, thank you. And to do that, you would hit the button and then see the icon with the 4 wheels and the X in the center of the car light up on your dash, correct?

Sweep

Without hitting the button you are All Wheel Drive, HIt the button and you are 4WD.

Don't hit the button unless you are in mud/snow/sand/ect. It doesn't sound like you are doing any off roading, so you will probably never need it.

Muti007

Thanks Sweep.

Sweep

No problem.

MSGX470

You are going to eat though tires much faster driving with the center diff. locked as the front and rear axles will be forced to turn at the same speed. I think the previous owner of my 08 GX may have been driving around this way due to the way the tires were worn when I received it. I do not engage the center diff. lock; except occasionally to confirm it is functioning properly and I have had no uneven tire wear thus far. Also I try to lock only on loose surfaces(grass, dirt, sand, gravel) to avoid tire chirp during turns.